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Sat, 11 May 2024 11:57:30 +0800 From: Miaohe Lin To: CC: , , , , , Subject: [PATCH -rc7] mm/huge_memory: mark huge_zero_page reserved Date: Sat, 11 May 2024 11:54:35 +0800 Message-ID: <20240511035435.1477004-1-linmiaohe@huawei.com> X-Mailer: git-send-email 2.33.0 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain X-Originating-IP: [10.173.135.154] X-ClientProxiedBy: dggems703-chm.china.huawei.com (10.3.19.180) To canpemm500002.china.huawei.com (7.192.104.244) X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: BA4D1140006 X-Stat-Signature: msrsk9qdbbwk3t44g6ftqe6i6ogm4qmp X-Rspam-User: X-HE-Tag: 1715399854-10915 X-HE-Meta: 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 51O6hhwU HKCTRSrbxLW5bqfAYGCuNN8wR+VRUCSHOKCiZopaoFs4v5C02ofrf3Gm0gCceO3s8V/WW8jfKP3UA0QiSA+gKxOv0hqIsn95BgkCcHhkGE/knICQshWKO788NS5jRrvuyN0QVyDp3Sl6ihEaCbidNkMqGeBp0jBsCwTQfmxNxmktq7jlKpX0UxDjivSuaVLqOs6VXusRf4q5NNQq7Du61TPu00ZLBxOLL4E4bR4HFvt+KwprEJInwleP51dG010as4KHxPvQYSj13HXgdqZx/RcO/yPh5xCVBq7eDhLnbmmRc0h2qwOwuspzhU3+q0Nc5gi5L X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: When I did memory failure tests recently, below panic occurs: kernel BUG at include/linux/mm.h:1135! invalid opcode: 0000 [#1] PREEMPT SMP NOPTI CPU: 9 PID: 137 Comm: kswapd1 Not tainted 6.9.0-rc4-00491-gd5ce28f156fe-dirty #14 RIP: 0010:shrink_huge_zero_page_scan+0x168/0x1a0 RSP: 0018:ffff9933c6c57bd0 EFLAGS: 00000246 RAX: 000000000000003e RBX: 0000000000000000 RCX: ffff88f61fc5c9c8 RDX: 0000000000000000 RSI: 0000000000000027 RDI: ffff88f61fc5c9c0 RBP: ffffcd7c446b0000 R08: ffffffff9a9405f0 R09: 0000000000005492 R10: 00000000000030ea R11: ffffffff9a9405f0 R12: 0000000000000000 R13: 0000000000000000 R14: 0000000000000000 R15: ffff88e703c4ac00 FS: 0000000000000000(0000) GS:ffff88f61fc40000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000055f4da6e9878 CR3: 0000000c71048000 CR4: 00000000000006f0 Call Trace: do_shrink_slab+0x14f/0x6a0 shrink_slab+0xca/0x8c0 shrink_node+0x2d0/0x7d0 balance_pgdat+0x33a/0x720 kswapd+0x1f3/0x410 kthread+0xd5/0x100 ret_from_fork+0x2f/0x50 ret_from_fork_asm+0x1a/0x30 Modules linked in: mce_inject hwpoison_inject ---[ end trace 0000000000000000 ]--- RIP: 0010:shrink_huge_zero_page_scan+0x168/0x1a0 RSP: 0018:ffff9933c6c57bd0 EFLAGS: 00000246 RAX: 000000000000003e RBX: 0000000000000000 RCX: ffff88f61fc5c9c8 RDX: 0000000000000000 RSI: 0000000000000027 RDI: ffff88f61fc5c9c0 RBP: ffffcd7c446b0000 R08: ffffffff9a9405f0 R09: 0000000000005492 R10: 00000000000030ea R11: ffffffff9a9405f0 R12: 0000000000000000 R13: 0000000000000000 R14: 0000000000000000 R15: ffff88e703c4ac00 FS: 0000000000000000(0000) GS:ffff88f61fc40000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000055f4da6e9878 CR3: 0000000c71048000 CR4: 00000000000006f0 The root cause is that HWPoison flag will be set for huge_zero_page without increasing the page refcnt. But then unpoison_memory() will decrease the page refcnt unexpectly as it appears like a successfully hwpoisoned page leading to VM_BUG_ON_PAGE(page_ref_count(page) == 0) when releasing huge_zero_page. Fix this issue by marking huge_zero_page reserved. So unpoison_memory() will skip this page. This will make it consistent with ZERO_PAGE case too. Fixes: 478d134e9506 ("mm/huge_memory: do not overkill when splitting huge_zero_page") Signed-off-by: Miaohe Lin Cc: --- mm/huge_memory.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 89f58c7603b2..a605bc0437cd 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -208,6 +208,7 @@ static bool get_huge_zero_page(void) __free_pages(zero_page, compound_order(zero_page)); goto retry; } + __SetPageReserved(zero_page); WRITE_ONCE(huge_zero_pfn, page_to_pfn(zero_page)); /* We take additional reference here. It will be put back by shrinker */ @@ -260,6 +261,7 @@ static unsigned long shrink_huge_zero_page_scan(struct shrinker *shrink, struct page *zero_page = xchg(&huge_zero_page, NULL); BUG_ON(zero_page == NULL); WRITE_ONCE(huge_zero_pfn, ~0UL); + __ClearPageReserved(zero_page); __free_pages(zero_page, compound_order(zero_page)); return HPAGE_PMD_NR; } -- 2.33.0